It could be many things GH. It really does require a physical to make sure it isnt thyroid, liver or many other things. Yes, it costs money but it really is the best way to start. I dont agree that just going on TRT is the answer until you eliminate alot of other things. At your age, you need to have physicals at least once a year. They really tell you alot. If your clear on all other things, and your test is tanked, you have the path forward from there. Your describing issues that could be other than just low T. Get checked out
Edit: Its your father in law. I wrote for you. Sorry